Apparatus for spatial and temporal control of temperature on a substrate

ABSTRACT

An apparatus for control of a temperature of a substrate has a temperature-controlled base, a heater, a metal plate, a layer of dielectric material. The heater is thermally coupled to an underside of the metal plate while being electrically insulated from the metal plate. A first layer of adhesive material bonds the metal plate and the heater to the top surface of the temperature controlled base. This adhesive layer is mechanically flexible, and possesses physical properties designed to balance the thermal energy of the heaters and an external process to provide a desired temperature pattern on the surface of the apparatus. A second layer of adhesive material bonds the layer of dielectric material to a top surface of the metal plate. This second adhesive layer possesses physical properties designed to transfer the desired temperature pattern to the surface of the apparatus. The layer of dielectric material forms an electrostatic clamping mechanism and supports the substrate.

FIELD OF THE INVENTION

The present invention relates to substrate supports. More particularly,the present invention relates to a method and apparatus for achievinguniform temperature distribution on a substrate during plasmaprocessing.

BACKGROUND OF THE INVENTION

A typical plasma etching apparatus comprises a reactor in which there isa chamber through which reactive gas or gases flow. Within the chamber,the gases are ionized into a plasma, typically by radio frequencyenergy. The highly reactive ions of the plasma are able to react withmaterial, such as a polymer mask on a surface of a semiconductor waferbeing processed into integrated circuits (IC's). Prior to etching, thewafer is placed into the chamber and held in proper position by a chuckor holder which exposes a top surface of the wafer to the plasma. Thereare several types of chucks (also sometimes called susceptors) known inthe art. The chuck provides an isothermal surface and serves as a heatsink for the wafer. In one type, a semiconductor wafer is held in placefor etching by mechanical clamping means. In another type of chuck, asemiconductor wafer is held in place by electrostatic force generated byan electric field between the chuck and wafer. The present invention isapplicable to both types of chucks.

In a typical plasma etching operation, the reactive ions of the plasmachemically react with portions of material on a face of thesemiconductor wafer. Some processes cause some degree of heating of thewafer, but most of the heating is caused by the plasma. The chemicalreaction rate between the materials in the plasma and the wafermaterial, on the other hand, is accelerated to some degree by thetemperature rise of the wafer. Local wafer temperature and rate ofchemical reaction at each microscopic point on the wafer are related toan extent that harmful unevenness in etching of material over a face ofthe wafer can easily result if the temperature of the wafer across itsarea varies too much. In most cases, it is highly desirable that etchingbe uniform to a nearly perfect degree since otherwise the IntegratedCircuit devices (ICs) being fabricated will have electroniccharacteristics that deviate from the norm more than is desirable.Furthermore, with each increase in the size of wafer diameter, theproblem of ensuring uniformity of each batch of ICs from larger andlarger wafers becomes more difficult. In some other cases, it would bedesirable to be able to control the surface temperature of the wafer toobtain a custom profile.

The problem of temperature rise of a wafer during reactive ion etching(RIE) is well known, and various attempts in the past to control thetemperature of a wafer during RIE have been tried. FIG. 1 illustratesone way to control wafer temperature during RIE. An inert coolant gas(such as helium or argon) is admitted at a single pressure within asingle thin space 102 between the bottom of the wafer 104 and the top ofthe chuck 106 which holds the wafer 104. This approach is referred to asbackside gas cooling.

There is generally no o-ring or other edge seal at the chuck perimeterexcept for a smooth sealing land extending from about 1 to 5 mm at theouter edge of the chuck 106 in order to reduce coolant leakage.Inevitably, without any elastomer seal, there is significant andprogressive pressure loss across the sealing land, such that the edge ofthe wafer 104 is inadequately cooled. The heat generated near the edgeof the wafer 104 must therefore flow significantly radially inwardbefore it can effectively be conducted away to the chuck. The arrows 106on top of the wafer 104 illustrate the incoming flux heating the wafer104. The flow of the heat in the wafer 104 is illustrated with thearrows 110. This explains why the edge zone of the chuck always tends tobe hotter than the rest of the surface. FIG. 2 illustrates a typicaltemperature distribution on the wafer 104. The pressure loss at theperipheral portions of the wafer 104 causes the wafer 104 to be muchhotter at the peripheral portions.

One way of dealing with the need for zone cooling is to vary the surfaceroughness or to cut a relief pattern to effectively change the localcontact area. Such a scheme can be used without backside coolant gas atall, in which case the contact area, surface roughness, and clamp forcedetermine the heat transfer. However the local contact area can only beadjusted by re-machining the chuck. Another way of dealing with the needfor zone cooling is to use coolant gas whose pressure is varied toincrease and fine tune thermal transport. However the relief pattern isstill substantially fixed. By dividing the surface of the chuck intodifferent zones, with or without small sealing lands as dividers, andsupplying separate cooling gasses to each zone, a greater degree ofindependent spatial control may be achieved. The gas supply to each zonemay have different composition or be set to a different pressure, thusvarying the thermal conduction. Each zone's operating conditions may beset under recipe control, or even dynamically stabilized during eachprocess step. Such schemes depend on redistributing the incoming heatflux from the plasma and driving it into different regions. This isrelatively effective at high power flux but will only give smalltemperature differentials at lower power flux. For instance, with about3 to 6 W per cm² of uniform flux and about 3 mm sealing land, it ispossible to get center to edge thermal gradients that lead to a 10° C.to 30° C. temperature increase near the wafer periphery. Thermalgradients of this magnitude can be very effective as a process controlparameter. For example, radial variations in plasma density orasymmetries in a reactor layout, which can affect critical processperformance metrics, are counteracted with an appropriate substratetemperature pattern. However, some processes may run at low power, forinstance poly gate processes, may have a flux of only 0.2 W per cm².Unless the average conduction is made extremely low, which is verydifficult to control and tends to result in inadequate overall cooling,then there will be only a very small differential of typically less than5° C.

Accordingly, a need exists for a method and apparatus for controllingthe temperature of semiconductor wafers during reactive ion etching andsimilar processes without requiring significant plasma heat flux. Aprimary purpose of the present invention is to solve these needs andprovide further, related advantages.

BRIEF DESCRIPTION OF THE INVENTION

An apparatus for control of a temperature of a substrate has atemperature-controlled base, a heater, a metal plate, a layer ofdielectric material. The heater is thermally coupled to an underside ofthe metal plate while being electrically insulated from the metal plate.The heater can be composed of multiple, independently controlled regionsto impart a spatially resolved thermal pattern. Temperature feedback foreach heater region is connected to appropriate power supplies, whichcontrols their thermal output. A first layer of adhesive material bondsthe metal plate and the heater to the top surface of the temperaturecontrolled base; the adhesive possesses physical properties that allowthe thermal pattern to be maintained under varying external processconditions. A second layer of adhesive material bonds the layer ofdielectric material to a top surface of the metal plate. The layer ofdielectric material forms an electrostatic clamping mechanism andsupports the substrate. High voltage is connected to the dielectricportion to accomplish electrostatic clamping of the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated into and constitute apart of this specification, illustrate one or more embodiments of thepresent invention and, together with the detailed description, serve toexplain the principles and implementations of the invention.

In the drawings:

FIG. 1 is a schematic elevational diagram of a support holding a waferunder process in accordance with the prior art;

FIG. 2 is a plot illustrating the temperature of a wafer and thepressure of a coolant in the apparatus of FIG. 1 in accordance with theprior art;

FIG. 3 is a diagram schematically illustrating a processing chamberhaving a base in accordance with one embodiment of the presentinvention.

FIG. 4 is a table illustrating the relationship between surfacetemperature range and parallelism of the layers in accordance with oneembodiment of the present invention.

FIG. 5 is a diagram schematically illustrating the apparatus surfacetemperature control scheme in accordance with one embodiment of thepresent invention.

FIG. 6 is a diagram schematically illustrating a processing chamberhaving a base in accordance with another embodiment of the presentinvention.

FIG. 7 is a diagram schematically illustrating a processing chamberhaving a base in accordance with yet another embodiment of the presentinvention.

FIG. 8 is a diagram schematically illustrating the apparatus surfacetemperature control scheme in accordance yet another embodiment of thepresent invention.

FIG. 9 is a diagram schematically illustrating a processing chamberhaving a base in accordance with yet another embodiment of the presentinvention.

FIG. 10 is a diagram schematically illustrating a cross-sectional viewof an electrical connector in accordance with one embodiment of thepresent invention.

FIG. 11 is a flow diagram schematically illustrating a method forspatially and temporally controlling the temperature on a substrateduring processing in accordance with one embodiment of the presentinvention.

FIGS. 12A, 12B, 12C are diagrams schematically illustrating across-sectional view of the apparatus being built in accordance with oneembodiment of the present invention.

FIG. 13 is a flow diagram illustrating a method for spatially andtemporally controlling the temperature on a substrate during processingin accordance with another embodiment of the present invention.

FIGS. 14A, 14B, 14C, 14D are diagrams schematically illustrating across-sectional view of the apparatus being built in accordance withanother embodiment of the present invention.

FIG. 15 is a flow diagram schematically illustrating a method forelectrically connecting a power supply to a heater and an electrostaticelectrode in a base in accordance with one embodiment of the presentinvention.

DETAILED DESCRIPTION

Embodiments of the present invention are described herein in the contextof a support for a substrate. Those of ordinary skill in the art willrealize that the following detailed description of the present inventionis illustrative only and is not intended to be in any way limiting.Other embodiments of the present invention will readily suggestthemselves to such skilled persons having the benefit of thisdisclosure. Reference will now be made in detail to implementations ofthe present invention as illustrated in the accompanying drawings. Thesame reference indicators will be used throughout the drawings and thefollowing detailed description to refer to the same or like parts.

In the interest of clarity, not all of the routine features of theimplementations described herein are shown and described. It will, ofcourse, be appreciated that in the development of any such actualimplementation, numerous implementation-specific decisions must be madein order to achieve the developer's specific goals, such as compliancewith application- and business-related constraints, and that thesespecific goals will vary from one implementation to another and from onedeveloper to another. Moreover, it will be appreciated that such adevelopment effort might be complex and time-consuming, but wouldnevertheless be a routine undertaking of engineering for those ofordinary skill in the art having the benefit of this disclosure.

The tunable electrostatic chuck of the present invention is an apparatusused for controlling the processing temperature of a substrate in plasmaenhanced and thermally enhanced reactions. The apparatus allows for afixed substrate temperature to be maintained under varying amounts ofexternal heat load from the process but also for deliberate change oftemperature as a function of time. The apparatus also allows forspatially resolved temperature signatures to be imparted and maintainedon the substrate during the process.

The tunable electrostatic chuck balances energy from heat sourceslocated within the apparatus in response to the thermal energy input ofthe external process, thereby maintaining a desired surface temperatureon the apparatus. Under static thermodynamic conditions, increasing thethermal energy from these heater sources will raise the surfacetemperature; decreasing the thermal energy will lower the surfacetemperature. Consequently, the control of the thermal energy in this wayprovides for temporal modification of the surface temperature. Inaddition, a spatially resolved heat source, i.e. a heat source withvaried thermal energy as a function of location, will provide thecapability of spatial temperature control. By controlling the surfacetemperature of the apparatus, the substrate that is well thermallycoupled to the surface of the apparatus will also benefit from the sametemperature control used by the apparatus.

The substrate temperature significantly affects the semiconductorprocess. The ability to provide temporal and spatial control of thesurface temperature of the semiconductor represents a very powerfulfeature for device fabrication. However, the heat transfer properties ofthe apparatus should be spatially uniform. Failure to accomplish thisheat transfer property may result in undesirable temperature signaturesthat cannot be corrected without employing very expensive andimpractical control schemes (e.g., a very high density of individualcontrol loops).

FIG. 3 illustrates a chamber 302 having an apparatus 304 for temporaland spatial control of the temperature of a substrate 306. The apparatus304 comprises a temperature-controlled base 308, a layer of adhesivematerial 310, a heater film 312, a metal plate 314, and a layer ofdielectric material 316.

The base 308 may include an actively cooled metal support member that isfabricated with length and width dimensions approximating those ofsubstrate 306. A cooling media maintains the temperature of base 308.The top surface of base 308 is machined to a high degree of flatness. Inone embodiment used with 200 mm or 300 mm silicon wafer, the variationmay be less than 0.0003″ throughout the top surface of base 308.

The top and bottom surfaces of metal plate 314 are made of a high degreeof flatness (within 0.0005″ surface variation) and parallelism (within0.0005″ surface variation). The thickness of metal plate 314 issufficient to adequately transfer the spatial pattern of a thermal heatsource (such as the heater film 312) directly underneath and in intimatecontact with the metal plate 314. In one embodiment, metal plate 314 mayinclude an aluminum plate having a thickness of about 0.040″.

Heater 312 may be a thin and flexible polyimide heater film bonded tothe bottom side of metal plate 314. Heater 312 may be constructed ofmultiple resistive elements, with a pattern layout designed toaccomplish spatial temperature control on the surface of the finishedassembly. To prevent any potential electrical problems, the heatingelements are electrically insulated from metal plate 314. Flexibleheater 312 is in intimate contact with metal plate 314. In oneembodiment, heater 312 includes a polyimide heater film having athickness of about 0.010″ with a surface variation within 0.0005″.

Both metal plate 314 and heater 312 are attached to base 308 using auniformly deposited, mechanically flexible adhesive 310. Metal plate 314and base 308 are separated by this layer of adhesive material 310 with ahigh degree of parallelism. The layer of adhesive material 310 hasheight dimension and thermal conductivity that defines an appropriateheat transfer between heating elements 312 and the external process. Theheat transfer coefficient may be determined by the relative power levelsemployed by the heating elements and external process. In oneembodiment, the layer of adhesive material 310 may include a siliconebond layer having a thermal transfer coefficient of about 0.17 W/m-° Kto about 0.51 W/m-° K. In one embodiment, the thickness of the layer ofadhesive material 310 may range from about 0.013″ to about 0.040″ withthickness variation (i.e., parallelism) within 0.001″. The importance ofthe thickness variation requirement is illustrated by the graph in FIG.4. For a fixed heat transfer coefficient (defined by nominal adhesivelayer thickness and adhesive layer thermal conductivity), the resultingsurface temperature non-uniformity will increase with increasingparallelism. To avoid problems with device fabrication resulting fromunwanted thermal non-uniformities, the adhesive layer thicknessvariation must be minimized, thereby implying an apparatus whose designcan achieve this requirement.

Returning to FIG. 3, a thin layer of dielectric material 316 may bedeposited (via CVD, spray-coating, etc . . . ) on the top surface ofmetal plate 314 to form an electrostatic clamping mechanism. Those ofordinary skills in the art will recognize that any conventionally usedmaterial with high field breakdown strength and chemical resistance tothe external process can be employed (e.g., aluminum oxide, aluminumnitride, yttrium oxide, etc.). The thickness and surface condition ofthe layer of dielectric material 316 may be defined so that the holdingforce and heat transfer characteristics impart the spatial temperaturepattern of the metal plate 314 to the substrate 306. In one embodiment,the layer of dielectric material 316 has a thickness of about 0.002″with a top surface variation within 0.001″.

Separately insulated electrical connections 322 and 324 may be made tothe heating elements of heater 312, and metal plate 314 (which iscoupled to the dielectric material 316) so as to provide control ofthese features with independent power supplies respectivelyElectrostatic Chuck (ESC) power supply 318 and heater power supply 320.An example of the insulated electrical connections are illustrated andlater described in FIG. 10.

Regional control of surface temperature is accomplished with one or moremeasurement probes that contact the metal plate through penetrations 508in the underlying layers, shown in FIG. 5. The probe 502 is part of afeedback loop 506 for control of one or more heating elements 510; theprobe output can be passed through a filtering scheme 504, if necessary,to eliminate any radio frequency noise on the measurement signal shouldthe apparatus be operated in an environment containing radio frequencypower. Given the small height dimension of the metal plate previouslydefined—necessary for adequate transfer of heater thermal pattern to thesurface of the apparatus—a suitably accurate estimate of the surfacetemperature can thereby be acquired.

FIG. 6 illustrates another embodiment of a chamber 602 having anapparatus 604 for temporal and spatial control of the temperature of asubstrate 606. The apparatus 604 comprises a temperature controlled base608, a layer of adhesive material 610, a heater film 612, a ceramicplate 614, and a layer of dielectric material 616. A cooling mediamaintains the temperature of base 608. A first power supply 620 supplieselectrical power to heater 612 via electrical connector 624. A secondpower supply supplies electrical power to the layer of dielectricmaterial 616 via electrical connector 622. Base 608, layer of adhesivematerial 610, heater 612, and layer of dielectric material 616 werepreviously described in FIG. 3. An example of the electrical connectionsis also illustrated and later described in FIG. 10. Heater 612 isdeposited to the underside of a ceramic plate 614 instead of metalplates 314, as described in FIG. 3. Ceramic plate 614 may include, forexample, aluminum nitride or aluminum oxide. The thickness of ceramicplate 614 is such that it adequately transfers the special pattern ofthe thermal heat source (heater 612) directly underneath and in intimatecontact with ceramic plate 614. Heater 612 does not have to beelectrically insulated from the ceramic plate 614. In one embodiment,base 608 has a top surface variation of about 0.0003″. The thickness oflayer of adhesive material 610 may range from about 0.013″ to about0.040″ with a top and bottom surface variation within 0.0003″ and aparallelism (top surface variation—bottom surface variation) of within0.001″. Heater 612 has a thickness of about 0.010″ with a bottom surfacevariation within 0.0005″. Ceramic plate 614 has a thickness of about0.040″ with top surface variation within 0.0005″ and a bottom surfacevariation within 0.0002″. Layer of dielectric material 616 (which iscoated on ceramic plate 614) has a thickness of about 0.002″ with a topsurface variation within 0.001″. The layer of dielectric material 616may be deposited (via CVD, spray-coating, etc . . . ) on the surface ofheater plate 614 (made of metal or ceramic). A conductive material ofsuitable properties would also need to be deposited to form a clampingelectrode.

FIG. 7 illustrates another embodiment of a chamber 702 having anapparatus 704 for temporal and spatial control of the temperature of asubstrate 706. The apparatus 704 comprises a temperature controlled base708, a layer of adhesive material 710, a heater film 712, a ceramic ormetal plate 714, a layer of adhesive material 715, and a layer ofdielectric material 716. A cooling media maintains the temperature ofthe base 708. A first power supply 720 supplies electrical power to theheater 712 via electrical connector 724. A second power supply 718supplies electrical power to the layer of dielectric material 716 viaelectrical connector 722. The base 708, the layers of adhesive material710, 715, and the heater 712 were previously described in FIGS. 3 and 6.The heater 712 is deposited to the underside of a ceramic or metal plate714. The dielectric layer 716 is a separate component containing aconductive electrode and appropriate insulating films to form anelectrostatic clamping mechanism, may have a thickness of about 0.040″,and may have a top and bottom surface variation within 0.001″. Theseparate and pre-fabricated layer of dielectric material 716 is attachedto the metal or ceramic plate 714 using a layer of adhesive material715. An example of the electrical connections is also illustrated anddescribed in FIG. 10.

Regional control of surface temperature is accomplished with one or moremeasurement probes 802 that contact the dielectric plate throughpenetrations 808 in the underlying layers, shown in FIG. 8. The probe802 is part of a feedback loop 806 for control of one or more heatingelements 810; the probe output can be passed through a filtering scheme804, if necessary, to eliminate any radio frequency noise on themeasurement signal should the apparatus be operated in an environmentcontaining radio frequency power. Given the small height dimension ofthe dielectric layer previously defined—necessary for adequate transferof heater thermal pattern to the surface of the apparatus—a suitablyaccurate estimate of the surface temperature can thereby be acquired.

FIG. 9 illustrates another embodiment of a chamber 902 having anapparatus 904 for temporal and spatial control of the temperature of asubstrate 906 in which the layer of adhesive material 910 includes a toplayer of bonding material 926, a solid plate 928, and a bottom layer ofbonding material 930. The apparatus 904 comprises atemperature-controlled base 908, a layer of adhesive material 910, aheater film 912, a metal or ceramic plate 914, a layer of adhesivematerial 913, and a layer of dielectric material 916. In one embodiment,base 908 has a top surface variation within 0.0003″. Heater film 912 mayhave a thickness of about 0.010″ with a bottom surface variation within0.0005″. Metal or ceramic plate 914 may have a thickness of about 0.040″with a top surface variation within 0.0005″ and a bottom surfacevariation within 0.0002″. Layer of adhesive material 913 may have athickness of about 0.004″. Layer of dielectric material 916 may have athickness of about 0.040″ with a top and bottom surface variation within0.001″.

A cooling media maintains the temperature of base 908 constant. A heaterpower supply 920 supplies electrical power to heater 912 via electricalconnector 924. A ESC power supply 918 supplies electrical power to themetal plate 913 or to dielectric material 916 via electrical connector922. Base 908, metal or ceramic plate 914, heater 912, layer of adhesivematerial 913, and layer of dielectric material 916 were previouslydescribed. An example of the electrical connections is also illustratedand later described in FIG. 10.

The layer of dielectric material 916 may be deposited (via CVD,spray-coating, etc . . . ) on the surface of heater plate 914 (made ofmetal or ceramic). If a metal plate is used, this same plate may beemployed for the clamp electrode. If a ceramic plate is used, then aconductive material of suitable properties would also need to bedeposited to form a clamping electrode.

Solid plate 928 sandwich between top layer of adhesive material 926 andbottom layer of adhesive material 930 is made of a plastic material(such as Vespel® or Torlon®). In one embodiment, the thickness of solidplate 928 may range from about 0.006″ to about 0.020″ with a top andbottom surface variation (parallelism) within 0.001″. The thermalconductivity of solid plate 928 may be about 0.17 W/mK. The thermalconductivity of solid plate 928 may be substantially similar to thethermal conductivity of the top and bottom layer of adhesive material926 and 930. The thermal conductivity of solid plate 928 may bedetermined by the relative power levels employed by heating elements 912and external process. The top layer of adhesive material 926 may have athickness of about 0.004″ with a surface variation within 0.0005″. Thebottom layer of adhesive material 930 may have a thickness ranging fromabout 0.006″ to about 0.020″ with a top and bottom surface variation(parallelism) within 0.001″. The bottom surface of solid plate 928 isthus attached to base 908 with mechanically flexible adhesive 930. Thetop surface of solid plate 928 is thus attached to heater 912 and metalor ceramic plate 914 with mechanically flexible adhesive 926. In anotherembodiment, the top surface of solid plate 928 may be machined to asurface variation within 0.0005″.

FIG. 10 illustrates a cross-sectional view of an electrical connector1000 supplying electrical power to a layer of dielectric material(Electrostatic Chuck—ESC) 1002. A pin assembly 1018 comprises a socket1014, a spring-loaded pin 1010, and a plastic insulator 1012. The ESCpower supply (not shown) is electrically coupled to the pinholder/socket 1014 forming the base of the vertical spring-loaded pin1010. The top end of the pin 1010 comes into electrical contact with abottom surface of the layer of dielectric material 1002. The plasticinsulator 1012 forms a shaft enclosing the socket 1014 and partiallyenclosing the spring loaded pin 1010. The top end tip of thespring-loaded pin 1010 vertically protrudes out of the plastic insulator1012. A portion of the heater layer 1004, the adhesive layer 1006, andthe base 1008 form a contiguous cavity 1020 in which the pin assembly1018 resides.

A non-electrically conductive bushing 1016 encloses a portion of the topend of the pin 1010 partially including a top end of the plasticinsulator 1012. The top part of the bushing 1016 is coupled to theheater layer 1004 with a bonding material 1022 such as siliconeadhesive. The bushing 1016 minimizes any anomalous thermal effectscaused by the physical contact between the dielectric material 1002 andthe top end of the pin 1010. The dielectric material 1002 is heated bythe heater 1004. The cooled base 1008 surrounds the pin assembly 1018.The bushing 1016 minimizes the amount of heat drawn from the dielectricmaterial 1002 towards the base 1008 via the pin assembly 1018. Thecavity 1020 is large enough to provide added space insulation betweenthe walls of the base 1008 and the outer surface of the plasticinsulator 1012.

FIG. 11 illustrates a flow diagram of a method for controlling thetemporal and spatial temperature of a substrate. At 1102, a metal plateis fabricated with length and width dimensions substantially equal tothe base. The top and bottom surfaces of the metal plate are made of ahigh degree of flatness and parallelism, for example, within 0.005″surface variation. In another embodiment, a ceramic plate may besubstituted for the metal plate.

At 1104, a heater is bonded to an underside of the metal plate. Theheater may include a thin and flexible heater film bonded to the bottomside of the metal plate. The heater may also include multiple resistiveelements, with a pattern layout designed to accomplish spatialtemperature control on the surface of the finished assembly. Forexample, regional thermal zone may be defined by one or more resistiveelements; the heater may include elements defining a radially outerregion and a radially inner region. To prevent any potential electricalproblems, the heating elements are electrically insulated from the metalplate. The heater is in intimate thermal contact with the metal plate.

Before attaching the heater and metal plate assembly to a base. At 1106,the top surface of the base is machined down to a high degree offlatness, for example, within 0.0003″ surface variation. At 1108, theheater and metal plate assembly are attached to the top surface of thebase with a layer of adhesive material.

In accordance with another embodiment, at 1110, the metal plate may befurther machined down after attachment to the base to provide a highdegree of flatness. In one embodiment, the top surface variation of themetal plate after machining is within 0.0005″.

At 1112, a thin layer of dielectric material 316 may be deposited on thetop surface of the metal plate to form an electrostatic clampingmechanism. Those of ordinary skill in the art will now recognize thatany conventionally used material with high field breakdown strength andchemical resistance to the external process can be used for dielectricmaterial 316 (e.g., aluminum oxide, aluminum nitride, yttrium oxide,etc.). In accordance with another embodiment, the dielectric materialmay be pre-fabricated and attached to the top surface of the metal platewith a layer of adhesive material.

At 1114, separately insulated electrical connections may be made to theheating elements of the heater and the metal plate (which is coupled tothe dielectric material) so as to provide control of these features withindependent power supplies. The electrical connection may beaccomplished using the electrical connector previously describedillustrated in FIG. 10.

FIGS. 12A, 12B, and 12C illustrate the method described in the flowdiagram of FIG. 11. FIG. 12A illustrates a metal plate 1202 and theattached heater 1204 assembly being bonded to a base 1206 using a layerof adhesive material 1208 as previously described at 1108. FIG. 12Billustrates the top surface of the metal plate 1202 being machine down aheight of about 0.040″ with a top surface variation within 0.0005″ afterbeing attached to base 1206. FIG. 12C illustrates a layer of dielectricmaterial 1210 being attached to the top surface of metal plate 1202 witha layer of silicone bonding material 1212. Alternatively, the layer ofdielectric material 1210 may be applied directly on the metal plate1202, using conventional deposition techniques, thereby eliminating thesilicone bonding material 1212.

FIG. 13 illustrates a flow diagram of a method for controlling thetemporal and spatial temperature of a substrate. At 1302, a metal plateis fabricated in a similar manner as previously described at 1102 inFIG. 11. At 1304, a heater is bonded to an underside of the metal platein a similar manner as previously described at 1104 in FIG. 11.

At 1306, the bottom surface of a solid plate such as a plastic plate isattached to the top surface of a base with a layer of adhesive material.At 1308, the top surface of the plastic plate is machine down to improvethe degree of flatness and parallelism. In one embodiment, the solidplate may have a thickness ranging from about 0.006″ to about 0.020″with a surface variation within 0.0005″.

At 1310, the metal plate and heater assembly is attached to the topsurface of the plastic plate with a layer of adhesive material.Alternatively, the layer of dielectric material may be applied directlyon the metal plate, using conventional deposition techniques, therebyeliminating the silicone bonding material.

At 1312, the top surface of the metal plate may also be machined downafter attachment to the base. This was previously described at 1110 inFIG. 11.

At 1314, the layer of dielectric material (ESC ceramic) is attached tothe top surface of the metal plate with a layer of adhesive material.This was previously described at 1112 in FIG. 11.

At 1316, separately insulated electrical connections may be made to theheating elements of the heater and the metal plate (which is coupled tothe dielectric material) so as to provide control of these features withindependent power supplies. This was previously described at 1114 inFIG. 1. The electrical connection may be accomplished using theelectrical connector previously described and illustrated in FIG. 10.

FIGS. 14A, 14B, 14C, and 14D illustrate the method described in the flowdiagram of FIG. 13. FIG. 14A illustrates a plastic plate 1402 beingbonded to a base 1404 using a layer of adhesive material 1406corresponding to 1306 in FIG. 13. FIG. 14B illustrates the top surfaceof the plastic plate 1402 being machined down to a height ranging fromabout 0.006″ to about 0.020″ after being attached to the base 1404 so asto achieve a top surface variation within 0.0005″. FIG. 14C illustratesa metal plate 1408 and heater 1410 assembly being attached to the topsurface of the plastic plate 1402 with a layer of adhesive material 1412corresponding to 1310 in FIG. 13. FIG. 14D illustrates the top surfaceof the metal plate 1408 being machined down to a thickness of about0.040″ with a top surface variation of about 0.0005″. The layer ofdielectric material 1414 is attached to the top surface of the metalplate 1408 with a layer of adhesive material 1416 corresponding to 1314in FIG. 13.

FIG. 15 illustrates a method for electrically connecting an electricalterminal of the electrostatic clamp of a wafer support having a base, abonding layer, a heater and a metal plate. At 1502, the non-electricallyconductive bushing is attached to the heater at the location defined byone of the electrostatic clamp's electrical terminations. At 1504, thespring-loaded pin is disposed within an insulating sleeve that exposesthe tip of the pin. At 1506, the pin with insulating sleeve is disposedin a cavity formed by the base, bonding layer, heater and metal plate,whereby the top portion of the sleeve overlaps the bottom portion of thebushing. At 1508, a top end of the electrical connector including avertical spring loaded pin contacts with a bottom surface of theelectrostatic clamp terminal.

While embodiments and applications of this invention have been shown anddescribed, it would be apparent to those skilled in the art having thebenefit of this disclosure that many more modifications than mentionedabove are possible without departing from the inventive concepts herein.The invention, therefore, is not to be restricted except in the spiritof the appended claims.

1. An apparatus for control of a temperature of a substrate comprising:a temperature-controlled base having a top surface, said base configuredto receive cooling media to control a temperature of said base; a platehaving a heater film thermally coupled to a bottom surface of the plate,the plate having a thickness adequate to transfer a spatial pattern ofthe heater film to the substrate, the plate having a bottom surface, thetop and bottom surfaces being substantially parallel to each other andhaving a variation in surface flatness within about 0.0005 inch; a firstlayer of adhesive, wherein the first layer of adhesive is configured tobond said plate and said heater film to the top surface of saidtemperature-controlled base, said first layer of adhesive having avariation in thickness within 0.001 inch; and a layer of dielectricmaterial bonded to a top surface of said plate, the layer of dielectricmaterial configured to form an electrostatic clamping mechanism forsupporting the substrate.
 2. The apparatus of claim 1 wherein the topsurface of said temperature-controlled base is substantially flat with avariation in flatness of less than 0.0003 inch, said layer of adhesiveis a mechanically flexible adhesive having a thickness no greater thanabout 0.04 inch and the layer of dielectric material has a variation insurface flatness within 0.001 inch.
 3. The apparatus of claim 1 whereina surface dimension of said plate is substantially similar to a surfacedimension of said temperature-controlled base.
 4. The apparatus of claim1 wherein said plate consists entirely of metal or entirely of ceramicand said first layer of adhesive has a thickness of 0.013 to 0.04 inch.5. The apparatus of claim 1 wherein said heater film has a variation insurface flatness within 0.0005 inch.
 6. The apparatus of claim 1 whereinsaid heater film includes resistive heating elements with a patternlayout providing spatial temperature control on the surface of the layerof dielectric material.
 7. The apparatus of claim 6 wherein said plateis a metal plate and said resistive heating elements are configured toform a pattern layout on said metal plate.
 8. The apparatus of claim 1wherein said first layer of adhesive has a thermal transfer coefficientof 0.17 W/m-° K to 0.51 W/m-° K.
 9. The apparatus of claim 1 whereinsaid plate is a ceramic plate of aluminum nitride or aluminum oxide. 10.The apparatus of claim 1 wherein said first layer of adhesive includes atop layer of bonding material, a plastic plate and a bottom layer ofbonding material and the plastic plate includes a top and bottomsurface, said top and bottom surface being substantially parallel toeach other to within about 0.001 inch and the plastic plate has athickness of 0.006 to 0.020 inch.
 11. The apparatus of claim 10 whereina thermal conductivity of said first layer of adhesive is based onrelative power levels employed by said heater film and an externalprocess.
 12. The apparatus of claim 10 wherein said bottom surface ofsaid plastic plate is bonded to said top surface of said base with thebottom layer of bonding material having a substantially high thermalconductivity and a thickness variation within 0.001 inch.
 13. Theapparatus of claim 12 wherein said top surface of said plastic plate isbonded to the heater film with the top layer of bonding material havinga substantially high thermal conductivity and a thickness variationwithin 0.0005 inch.
 14. The apparatus of claim 1 further comprising anelectrical connector having: a vertical spring loaded pin having a topend in contact with a bottom surface of the layer of dielectricmaterial, said vertical spring loaded pin disposed in a cavity of saidbase, and first layer of adhesive layer, and said heater film and saidplate; and a bushing configured to enclose a portion of said top end ofsaid pin, said bushing being thermally conductive and thermally coupledto said heater film and said dielectric layer and said bushing beingelectrically non-conductive.
 15. The apparatus of claim 14 furthercomprising a socket configured to hold a bottom end of said pin.
 16. Theapparatus of claim 15 further comprising a plastic insulator coverconfigured to cover said socket and a portion of said pin to expose saidtop end of said pin.
 17. The apparatus of claim 14 wherein said bushingis configured to electrically insulate said top end of said pin from awall of said cavity in said base and to transfer an amount of heat fromsaid heater film to said dielectric layer.
 18. The apparatus of claim 1wherein the heater film is in contact with the underside of the plateand the layer of dielectric material is bonded to the top surface of theplate with a second layer of adhesive.
 19. The apparatus of claim 1wherein the base is made of metal and the plate is an aluminum platewith a thickness of 0.040 inch and variation in surface flatness of topand bottom surfaces thereof within 0.0005 inch.